JP5242081B2 - Multi-piece solid golf ball - Google Patents

Description

  The present invention relates to a multi-piece solid golf ball formed by laminating a core, a surrounding layer, an intermediate layer, and a cover. More specifically, the present invention is excellent in flying performance and professional performance for professionals and advanced players. For good multi-piece solid golf balls.

  Conventionally, various golf balls have been developed as golf balls for professionals and advanced players, and above all, from the point of achieving superior flight distance performance in the high head speed area and controllability in iron shots and approach shots, Multi-piece solid golf balls having a function that optimizes the hardness relationship of each layer of the intermediate layer and the cover layer covering the core are widely used. In addition to the flying performance, the feel at the time of hitting and the spin amount of the ball after hitting the club greatly affect the control of the ball. It is also an important theme to optimize the thickness and hardness of the steel. In addition, repeated hitting durability resulting from repeated hitting of the golf ball with various clubs and generation of crusts (scratch resistance) observed on the ball surface are also required. The aspect of protection is also an important theme in developing the ball.

  As such a golf ball, there has been proposed a three-piece solid golf ball in which an outer cover of JP-A-2004-180822 is formed using thermoplastic polyurethane as a main material. However, with this golf ball, there is an insufficient aspect of realizing low spin when hit by a driver, and it has been impossible to obtain a satisfactory flight distance from professionals and advanced players, and the durability is also poor. .

  On the other hand, for further pursuit of golf ball flight, etc., each layer in the ball structure is made into four layers, that is, the intermediate layer covering the core and the cover layer are made into three layers, and the ball structure is internally changed into multiple layers. Proposals have been made. For example, JP-A-9-248351, JP-A-10-127818, JP-A-10-127817, JP-A-10-295852, JP-A-10-328325, JP-A-10-328326, JP-A-10-328327, JP-A-10-328328, JP-A-11-4916, and the like have been proposed.

  However, these proposed golf balls have a poor balance of flight distance and controllability as golf balls suitable for advanced players, and low spin at the time of driver hitting is insufficient to achieve the total flight distance. There is a limit to increasing. Further, in these proposed golf balls, it is difficult to achieve both a low spin effect, resilience and durability.

JP 2004-180822 A JP-A-9-248351 Japanese Patent Laid-Open No. 10-127818 Japanese Patent Laid-Open No. 10-127819 JP-A-10-295852 JP 10-328325 A Japanese Patent Laid-Open No. 10-328326 JP 10-328327 A JP-A-10-328328 Japanese Patent Laid-Open No. 11-4916

  The present invention has been made in view of the above circumstances, and provides a multi-piece solid golf ball with excellent flying resistance and controllability that can be satisfied by professionals and advanced players, as well as excellent durability against cracking and abrasion resistance during repeated impacts. The purpose is to do.

  In the present invention, the basic structure of the golf ball design is that polyurethane is the outermost layer and the outer layer covering the core has a multilayer structure of three layers or more of an envelope layer, an intermediate layer, and a cover. The cover is made of relatively soft polyurethane as the outermost layer, so that the approach spin performance that can be satisfied by professionals and advanced players and a high level of abrasion resistance can be obtained. By forming the intermediate layer as a relatively hard and strong ionomer material, the intermediate layer can achieve both high resilience and durability and low spin during full shot. The envelope layer uses a material formed with a specific resin mixture as a main material, so that it has low spin at the time of hitting W # 1 and high durability against repeated hitting. And the surface of each layer of an intermediate | middle layer-cover has a hard-soft hardness relationship in order. The above-described conventional problems can be solved by a synergistic effect of the material and hardness relationship of each layer. That is, when the golf ball of the present invention is used by professionals and advanced players, it has a sufficiently satisfactory flight and controllability, and also exhibits excellent cracking durability and abrasion resistance during repeated hitting. The effects are unexpected, and therefore, the present inventor has found that the above-described problem can be solved by the above-described configuration of the present invention, and has completed the present invention.

Accordingly, the present invention provides the following multi-piece solid golf ball.
[1] A core composed of a single layer, an envelope layer having a thickness of 1.0 to 4.0 mm for covering the core, an intermediate layer having a thickness of 0.7 to 2.0 mm for covering the core, and a covering layer for covering the same. In the multi-piece solid golf ball provided with a cover having a large number of dimples formed on the surface, the core is formed mainly of polybutadiene , and the core has a diameter of 31 mm or more. The amount of deflection (mm) from the initial load of 98 N (10 kgf) to the final load of 1,275 N (130 kgf) is in the range of 2.0 mm or more and 5.0 mm or less. Metal ion neutralized product of saturated carboxylic acid binary random copolymer and / or olefin-unsaturated carboxylic acid binary random copolymer, and (b) olefin-unsaturated carboxylic acid-unsaturated catalyst The mass ratio of the boronic acid ternary random copolymer and / or the metal ion neutralized product of the olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ternary random copolymer is 100: 0 to 0: 100. A base resin formulated as
(E) Non-ionomer thermoplastic elastomer and 100 parts by mass of a resin component formulated so as to have a mass ratio of 100: 0 to 50:50,
(C) 5-80 parts by mass of a fatty acid having a molecular weight of 280-1500 and / or a derivative thereof;
(D) The base resin and a basic inorganic metal compound capable of neutralizing an unneutralized acid group in the component (c) are formed as a main material, a mixture containing 0.1 to 10 parts by mass as an essential component, The intermediate layer is formed mainly of a resin material, and the cover is
(A) a thermoplastic polyurethane material;
(B) an isocyanate mixture in which an isocyanate compound (b-1) having two or more isocyanate groups as a functional group in one molecule is dispersed in a thermoplastic resin (b-2) that does not substantially react with isocyanate; And the cover has a durometer D hardness of 46 or more and 54 or less, and the intermediate layer and the cover have a surface hardness (durometer D hardness) of intermediate layer surface hardness> A multi-piece solid golf ball that satisfies the condition of the cover surface hardness and the thickness of the envelope layer, intermediate layer, and cover satisfies the condition of cover thickness <interlayer thickness <envelop layer thickness .
[2] The multi-piece solid golf ball according to [1], wherein the hardness relationship between the envelope layer and the intermediate layer satisfies the condition of envelope layer surface hardness <intermediate layer surface hardness.

  According to the golf ball of the present invention, by using a specific resin mixture as the envelope layer and using a polyurethane material as the main material for the cover, by optimizing the surface hardness of each layer of the intermediate layer and the cover as described above, The ball has low spin at the time of a full shot by the driver, further increases the flight distance of the ball and has good controllability, and also has excellent crack durability and scratch resistance at repeated hits, professional and advanced It is a multi-layered golf ball that is very useful as a golf ball for the user.

Hereinafter, the present invention will be described in more detail.
As shown in FIG. 1, the multi-piece solid golf ball of the present invention includes a core 1, an envelope layer 2 that covers the core, an intermediate layer 3 that covers the envelope layer, and an intermediate layer that covers the intermediate layer. A golf ball G having four or more layers having a cover 4 to be processed. In addition, many dimples D are usually formed on the surface of the cover 4. As shown in FIG. 1, the core 1 is limited to a single layer, but the intermediate layer 3 is not limited to a single layer, and can be formed in a plurality of layers of two or more layers.

The diameter of the core in the present invention is 31 mm or more, preferably 31 mm or more and 38 mm or less, more preferably 32.5 mm or more and 37 mm or less, and further preferably 34 mm or more and 36 mm or less. If the core diameter deviates from this range, the initial velocity of the ball may become low, or the flight distance may not be extended due to the low spin effect after hitting the ball.

  The surface hardness of the core is not particularly limited, but is preferably 45 to 65 in terms of durometer D hardness (measured by a type D durometer based on ASTM D2240, and the same meaning for the explanation of hardness in each layer below). Preferably they are 50 or more and 60 or less, More preferably, they are 52 or more and 58 or less. Below the above range, the rebound characteristics of the core may not be sufficient and the flight distance may not be extended, or the crack durability during repeated impacts may be poor. On the other hand, if the above range is exceeded, the shot feeling when a full shot is made may become too hard, or the spin amount may become too large to increase the flight distance.

Amount of deflection when the core is load-bearing, i.e., the core, the amount of deflection of the initial load 98 N (10 kgf) until a final load 1,275N (130kgf) (mm) is, 2.0 mm or more It is adjusted to a range of 5.0 mm or less , preferably 2.3 mm or more and 4.4 mm or less, more preferably 2.6 mm or more and 3.8 mm or less. If this value is too large, the rebound of the core will be insufficient and the flight distance will be insufficient, and the cracking durability at the time of repeated hitting may deteriorate. On the other hand, if this value is too small, the hit feeling at the time of a full shot may become too hard, or the spin amount may become too large to increase the flight distance.

  A rubber material can be used as the main material as the core material having the surface hardness and deflection as described above. For example, in addition to the rubber material, it can be formed using a rubber composition containing a co-crosslinking agent, an organic peroxide, an inert filler, an organic sulfur compound and the like. And it is preferable to use polybutadiene as a base rubber of this rubber composition.

  The rubber component polybutadiene has a cis-1,4-bond in the polymer chain of 60% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and most preferably 95% by mass or more. Is preferred. If there are too few cis-1,4-bonds in the bonds in the molecule, the resilience may decrease.

  The content of 1,2-vinyl bonds contained in the polybutadiene is preferably 2% by mass or less, more preferably 1.7% by mass or less, and further preferably 1.5% by mass or less in the polymer chain. It is. If the content of 1,2-vinyl bond is too large, the resilience may be lowered.

  The polybutadiene used in the present invention is preferably synthesized with a rare earth element-based catalyst or a Group VIII metal compound catalyst from the viewpoint of obtaining a vulcanized molded product of a rubber composition having good resilience. In particular, those synthesized with a rare earth element-based catalyst are preferable.

  Such a rare earth element-based catalyst is not particularly limited. For example, a catalyst obtained by combining a lanthanum series rare earth element compound with an organoaluminum compound, an alumoxane, a halogen-containing compound, and a Lewis base as necessary. Can be mentioned.

  Examples of the lanthanum series rare earth element compounds include metal halides having an atomic number of 57 to 71, carboxylates, alcoholates, thioalcolates, and amides.

  In the present invention, in particular, the use of a neodymium-based catalyst using a neodymium compound as a lanthanum series rare earth element compound results in a polybutadiene rubber having a high content of 1,4-cis bonds and a low content of 1,2-vinyl bonds. These are preferable because they are obtained with excellent polymerization activity. Specific examples of these rare earth element-based catalysts are described in JP-A-11-35633, JP-A-11-164912, and JP-A-2002-293996. Can be preferably mentioned.

  In order to improve the resilience, the polybutadiene synthesized using a lanthanum series rare earth element compound-based catalyst is preferably contained in the rubber component in an amount of 10% by mass or more, preferably 20% by mass or more, particularly 40% by mass or more. .

  In addition to the polybutadiene, other rubber components can be blended with the rubber base material as long as the effects of the present invention are not impaired. Examples of the rubber component other than the polybutadiene include polybutadiene other than the polybutadiene, and other diene rubbers such as styrene butadiene rubber, natural rubber, isoprene rubber, and ethylene propylene diene rubber.

  Examples of the co-crosslinking agent include unsaturated carboxylic acids and unsaturated carboxylic acid metal salts.

  Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, and fumaric acid. Acrylic acid and methacrylic acid are particularly preferably used.

  Although it does not specifically limit as a metal salt of unsaturated carboxylic acid, For example, what neutralized the said unsaturated carboxylic acid with the desired metal ion is mentioned. Specific examples include zinc salts such as methacrylic acid and acrylic acid, magnesium salts, and the like. In particular, zinc acrylate is preferably used.

  The unsaturated carboxylic acid and / or metal salt thereof is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, preferably as an upper limit with respect to 100 parts by mass of the base rubber. Is 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 45 parts by mass or less, and most preferably 40 parts by mass or less. If the blending amount is too large, it may become too hard and unbearable feel may occur, and if the blending amount is too small, the resilience may decrease.

  Commercially available products can be used as the organic peroxide. For example, Park Mill D (manufactured by NOF Corporation), Perhexa 3M (manufactured by NOF Corporation), Luperco 231XL (manufactured by Atchem Co.) and the like are suitable. Can be used. These may be used alone or in combination of two or more.

  The organic peroxide is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, still more preferably 0.5 parts by mass or more, and most preferably 0, with respect to 100 parts by mass of the base rubber. 0.7 parts by mass or more, and the upper limit is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, still more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less. If the blending amount is too large or too small, it may not be possible to obtain suitable feel, durability and resilience.

  As the inert filler, for example, zinc oxide, barium sulfate, calcium carbonate and the like can be suitably used. These may be used individually by 1 type and may use 2 or more types together.

  The blending amount of the inert filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and the upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass with respect to 100 parts by mass of the base rubber. Hereinafter, it is more preferably 30 parts by mass or less. If the blending amount is too large or too small, it may not be possible to obtain an appropriate mass and suitable resilience.

  Furthermore, an anti-aging agent can be blended as necessary. For example, as a commercial product, Nocrack NS-6, NS-30 (manufactured by Ouchi Shinsei Chemical Co., Ltd.), Yoshinox 425 (Yoshitomi Pharmaceutical Co., Ltd.) )) And the like. These may be used individually by 1 type and may use 2 or more types together.

  The blending amount of the anti-aging agent is preferably 0 parts by mass or more, more preferably 0.05 parts by mass or more, still more preferably 0.1 parts by mass or more, preferably as an upper limit with respect to 100 parts by mass of the base rubber. 3 parts by mass or less, more preferably 2 parts by mass or less, still more preferably 1 part by mass or less, and most preferably 0.5 parts by mass or less. If the amount is too large or too small, it may not be possible to obtain suitable resilience and durability.

  The core is preferably blended with an organic sulfur compound in order to improve the resilience of the golf ball and increase the initial velocity of the golf ball.

  The organic sulfur compound is not particularly limited as long as it can improve the resilience of the golf ball, and examples thereof include thiophenols, thionaphthols, halogenated thiophenols, and metal salts thereof. More specifically, pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, parachlorothiophenol, zinc salt of pentachlorothiophenol, zinc salt of pentafluorothiophenol, zinc salt of pentabromothiophenol, Examples include zinc salt of parachlorothiophenol, diphenyl polysulfide having 2 to 4 sulfur atoms, dibenzyl polysulfide, dibenzoyl polysulfide, dibenzothiazoyl polysulfide, dithiobenzoyl polysulfide, etc., especially zinc salt of pentachlorothiophenol, diphenyl Disulfide is preferably used.

  The amount of such an organic sulfur compound is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and the upper limit is preferably 5 parts by mass or less with respect to 100 parts by mass of the base rubber. It is recommended that the amount be 4 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2.5 parts by mass or less. If the blending amount is too large, the effect reaches a peak, and further effects may not be observed. If the blending amount is too small, the blending effect may not be sufficiently achieved.

Next, the envelope layer will be described below.
The material hardness of the envelope layer is not particularly limited, but is preferably in the range of 40 to 62, preferably 47 to 60, and more preferably 50 to 58 in terms of durometer D hardness. If it is softer than the above range, the spin distance may be excessively applied during a full shot and the flight distance may not be extended. On the other hand, if it is too hard than the above range, the durability to cracking upon repeated impacts may be deteriorated or the feel at impact may become too hard. The thickness of the surrounding layer is 1.0mm or more 4.0mm or less, preferably 1.2mm or more 3.0mm or less, more preferably 1.4mm or more 2.0mm or less. Outside this range, the low spin effect due to the driver (W # 1) hit may not be sufficient and the flight distance may not be extended.

  Although there is no restriction | limiting in particular about the surface hardness of an envelope layer, It is preferable to set it as 50 or more and 70 or less by durometer D hardness, More preferably, it is 53 or more and 67 or less, More preferably, it is 55 or more and 63 or less. If the value is too smaller than the above range, the spin distance may be excessively applied during a full shot and the flight distance may not be extended. On the other hand, if the value is larger than the above range, the durability to cracking at the time of repeated hitting may deteriorate, or the hit feeling may become too hard. The surface of the envelope layer is preferably softer than the surface of the intermediate layer, and the degree thereof is not particularly limited, but is preferably 3 to 20 in terms of durometer D hardness, more preferably 5 to 18 and even more preferably. Is 7 or more and 16 or less. If the envelope layer surface deviates from the above range and the surface of the envelope layer is too soft than the intermediate layer surface, the rebound of the ball may become low, or the spin amount may increase and the flight distance may not increase.

The main material of the envelope layer in the present invention is (a) a metal ion neutralized product of an olefin-unsaturated carboxylic acid binary random copolymer and / or an olefin-unsaturated carboxylic acid binary random copolymer, and (b ) Mass ratio of olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ternary random copolymer and / or metal ion neutralized product of olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ternary random copolymer A base resin formulated to be 100: 0 to 0: 100,
(E) Non-ionomer thermoplastic elastomer and 100 parts by mass of a resin component formulated so as to have a mass ratio of 100: 0 to 50:50,
(C) 5-80 parts by mass of a fatty acid having a molecular weight of 280-1500 and / or a derivative thereof;
(D) It is the mixture which mix | blended 0.1-10 mass parts of basic inorganic metal compounds which can neutralize the unneutralized acid group in the said base resin and (c) component as an essential component.

  Here, the olefin in the base resin preferably has a carbon number of usually 2 or more and an upper limit of 8 or less, particularly 6 or less, regardless of whether the component is the component (a) or the component (b). Examples thereof include ethylene, propylene, butene, pentene, hexene, heptene, octene and the like, and ethylene is particularly preferable.

  Moreover, as unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid etc. can be mentioned, for example, It is especially preferable that they are acrylic acid and methacrylic acid.

  Further, as the unsaturated carboxylic acid ester, the lower alkyl ester of the unsaturated carboxylic acid described above is preferable. Specifically, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, acrylic Examples include ethyl acrylate, propyl acrylate, and butyl acrylate, and butyl acrylate (n-butyl acrylate and i-butyl acrylate) is particularly preferable.

  Component (a) olefin-unsaturated carboxylic acid binary random copolymer and component (b) olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer (hereinafter referred to as component (a) and ( The copolymers in the component b) are collectively referred to as random copolymers) and can be obtained by adjusting the materials described above and carrying out random copolymerization by a known method.

  It is recommended that the random copolymer has an adjusted unsaturated carboxylic acid content (acid content). Here, the content of the unsaturated carboxylic acid contained in the random copolymer of component (a) is preferably 4% by mass or more, more preferably 6% by mass or more, still more preferably 8% by mass or more, and particularly preferably 10%. It is recommended that the upper limit is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 18% by mass or less, and particularly preferably 15% by mass or less.

  Similarly, the content of the unsaturated carboxylic acid contained in the random copolymer of the component (b) is preferably 4% by mass or more, more preferably 6% by mass or more, still more preferably 8% by mass or more, and the upper limit is preferably Is recommended to be 15% by mass or less, more preferably 12% by mass or less, and still more preferably 10% by mass or less. If the acid content of the random copolymer is too low, the resilience may be reduced, and if it is too high, the processability may be reduced.

  (A) Metal ion neutralized product of component olefin-unsaturated carboxylic acid binary random copolymer and (b) Component olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer metal ion The neutralized product (hereinafter, the metal ion neutralized product of the copolymer in the component (a) and the component (b) is collectively referred to as the metal ion neutralized product of the random copolymer) is contained in the random copolymer. It can be obtained by partially neutralizing the acid group of with a metal ion.

Here, examples of metal ions that neutralize acid groups include Na ⁺ , K ⁺ , Li ⁺ , Zn ⁺⁺ , Cu ⁺⁺ , Mg ⁺⁺ , Ca ⁺⁺ , Co ⁺⁺ , Ni ⁺⁺ , and Pb. ^{++ and the} like can be mentioned, preferably Na ⁺ , Li ⁺ , Zn ⁺⁺ , Mg ^{++ and the} like can be preferably used, and Na ⁺ is preferably used from the viewpoint of improving the resilience. It is.

  In order to obtain a metal ion neutralized product of the random copolymer, the random copolymer may be neutralized with the metal ion. For example, the metal ion formate, acetate, nitrate, carbonate A method of neutralizing using a compound such as a salt, bicarbonate, oxide, hydroxide and alkoxide can be employed. The neutralization degree with respect to the random copolymer of these metal ions is not specifically limited.

  As the metal ion neutralized product of the random copolymer, a sodium ion neutralized ionomer resin can be suitably used, and it is easy to increase the melt flow rate of the material and adjust it to the optimum melt flow rate described later. Yes, moldability can be improved.

  As the base resin of the component (a) and the component (b), commercially available products may be used. For example, as the random copolymer of the component (a), Nucrel 1560, 1214, 1035 (all are Mitsui). -DuPont Polychemical Co., Ltd.), ESCOR 5200, 5100, 5000 (all manufactured by EXXONMOBIL CHEMICAL), etc., as the random copolymer of component (b), for example, Nukurel AN4311, AN43318 (both Mitsui, DuPont) Polychemical Co., Ltd.), ESCOR ATX325, ATX320, ATX310 (all manufactured by EXXONMOBIL CHEMICAL), and the like.

  Moreover, as a metal ion neutralized product of the random copolymer of component (a), for example, Himiran 1554, 1557, 1601, 1605, 1706, and AM7311 (all manufactured by Mitsui DuPont Polychemical Co., Ltd.), Surlyn 7930 (manufactured by DuPont, USA), Iotech 3110, 4200 (manufactured by EXXONMOBIL CHEMICAL), etc., as the metal ion neutralized product of the random copolymer of component (b), for example, Himilan 1855, 1856, AM7316 (All are made by Mitsui DuPont Polychemical Co., Ltd.), Surlyn 6320, 8320, 9320, 8120 (all manufactured by DuPont, USA), Iotech 7510, 7520 (all manufactured by EXXONMOBIL CHEMICAL), etc. Can do. Examples of the sodium neutralized ionomer resin suitable as the metal ion neutralized product of the random copolymer include Himiran 1605, 1601 and 1555, Surlyn 8120, and the like.

  In the preparation of the base resin, the blending ratio of the component (a) and the component (b) is preferably 100: 0 to 0: 100, more preferably 100: 0 to 25:75, and still more preferably, by mass ratio. It is necessary to make it 100: 0 to 50:50, particularly preferably 100: 0 to 75:25, and most preferably 100: 0. When the blending amount of the component (a) is too small, the resilience of the molded material is lowered.

  In addition to the above preparation, the base resin can further improve the moldability by adjusting the blending ratio of the random copolymer and the metal ion neutralized product of the random copolymer. Copolymer: Random copolymer metal ion neutralized product is preferably 0: 100 to 60:40, more preferably 0: 100 to 40:60, still more preferably 0: 100 to 20:80, particularly preferably. Is recommended to be 0: 100. If the amount of the random copolymer is too large, the moldability during mixing may decrease.

  The following component (e) can be added to the base resin. The component (e) is a non-ionomer thermoplastic elastomer. This component is a component for further improving the feeling and resilience at the time of impact, and specifically includes olefin elastomers, styrene elastomers, polyester elastomers, urethane elastomers, polyamide elastomers, and the like. From the point that the resilience can be further increased, polyester elastomers and olefin elastomers, in particular, olefin elastomers composed of a thermoplastic block copolymer containing a crystalline polyethylene block as a hard segment are preferably used. be able to.

  As the component (e), commercially available products may be used. Specific examples include Dynalon (manufactured by JSR) and polyester elastomers such as Hytrel (manufactured by Toray DuPont).

  The amount of the component (e) is preferably 0 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and particularly preferably 20 parts by mass with respect to 100 parts by mass of the base resin of the present invention. The upper limit is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 50 parts by mass or less, and particularly preferably 40 parts by mass or less. If the blending amount is too large, the compatibility of the mixture is lowered, and the durability of the golf ball may be significantly lowered.

  Next, the component (c) shown below can be added to the base resin. The component (c) is a fatty acid having a molecular weight of 280 to 1500 or a derivative thereof, and has a very small molecular weight as compared with the base resin, and appropriately adjusts the melt viscosity of the mixture, and contributes particularly to improvement of fluidity. It is. The component (c) contains a relatively high content of acid groups (derivatives) and can suppress excessive rebound loss.

  The molecular weight of the fatty acid or derivative thereof as component (c) is 280 or more, preferably 300 or more, more preferably 330 or more, still more preferably 360 or more, and the upper limit is 1500 or less, preferably 1000 or less, more preferably 600 or less. More preferably, it is necessary to be 500 or less. If the molecular weight is too low, the heat resistance cannot be improved, and if it is too high, the fluidity cannot be improved.

  Examples of the fatty acid or fatty acid derivative thereof as component (c) include unsaturated fatty acids (derivatives) containing a double bond or triple bond in the alkyl group, and saturated fatty acids in which the bond in the alkyl group is composed of only a single bond. (Derivatives) can be suitably used as well, but in any case, the number of carbon atoms in one molecule is usually 18 or more, preferably 20 or more, more preferably 22 or more, still more preferably 24 or more, and the upper limit is 80 or less. It is recommended that it is preferably 60 or less, more preferably 40 or less, and still more preferably 30 or less. If the number of carbon atoms is too small, improvement in heat resistance cannot be achieved, and there is too much content of acid groups, resulting in less fluidity improvement due to interaction with acid groups contained in the base resin. There is. On the other hand, when the number of carbon atoms is too large, the molecular weight increases, and thus the effect of fluidity modification may not be noticeable.

  Here, specific examples of the fatty acid (c) include stearic acid, 12-hydroxystearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, lignoceric acid, and the like. Examples include stearic acid, arachidic acid, behenic acid, lignoceric acid, and more preferably behenic acid.

Moreover, the fatty acid derivative of the said (c) component can illustrate the metal soap which substituted the proton contained in the acid group of the fatty acid mentioned above with the metal ion. In this case, examples of the metal ions include Na ⁺ , Li ⁺ , Ca ⁺⁺ , Mg ⁺⁺ , Zn ⁺⁺ , Mn ⁺⁺ , Al ⁺⁺⁺ , Ni ⁺⁺ , Fe ⁺⁺ , Fe ⁺⁺⁺ , Examples thereof include Cu ⁺⁺ , Sn ⁺⁺ , Pb ⁺⁺ , and Co ⁺⁺ , and Ca ⁺⁺ , Mg ⁺⁺ , and Zn ⁺⁺ are particularly preferable.

  Specific examples of the fatty acid derivative (c) include magnesium stearate, calcium stearate, zinc stearate, 12-hydroxy magnesium stearate, 12-hydroxy calcium stearate, zinc 12-hydroxy stearate, magnesium arachidate, and arachidin. Calcium acid, Zinc arachidate, Magnesium behenate, Calcium behenate, Zinc behenate, Magnesium lignocerate, Calcium lignocerate, Zinc lignocerate, etc. Especially magnesium stearate, calcium stearate, zinc stearate , Magnesium arachidate, calcium arachidate, zinc arachidate, magnesium behenate, calcium behenate, zinc behenate, lignoserine Magnesium, calcium lignoceric acid, can be preferably used lignoceric acid zinc.

  (D) component can be added as a basic inorganic metal compound which can neutralize the acid group in said base resin and (c) component. When this component (d) is not blended, the metal soap-modified ionomer resin (for example, only the metal soap-modified ionomer resin described in the above-mentioned patent gazette) is used alone and included in the metal soap and ionomer resin during heating and mixing. The unneutralized acid groups that are exchanged react to generate a large amount of fatty acid, and the generated fatty acid has low thermal stability and is easily vaporized at the time of molding. Adhering may cause problems such as significantly lowering the adhesion of the coating film and reducing the resilience of the resulting molded article.

  In order to solve such problems, as the component (d), a basic inorganic metal compound that neutralizes the acid group contained in the base resin and the component (c) is blended as an essential component, and the resilience of the molded product It is intended to improve.

  That is, the component (d) is blended as an essential component in the material, so that the base resin and the acid group in the component (c) are not only appropriately neutralized, but also synergistic by optimization of each component. With this effect, the thermal stability of the mixture can be increased, and good moldability can be imparted and resilience can be improved.

  Here, the basic inorganic metal compound of component (d) is highly reactive with the base resin and does not contain an organic acid in the reaction by-product, so that the neutralization degree of the mixture can be increased without impairing thermal stability. It is recommended that it be raised.

The metal ions in the basic inorganic metal compound (d) are, for example, Li ⁺ , Na ⁺ , K ⁺ , Ca ⁺⁺ , Mg ⁺⁺ , Zn ⁺⁺ , Al ⁺⁺⁺ , Ni ⁺⁺ , Fe ⁺⁺ , Fe ⁺⁺⁺ , Cu ⁺⁺ , Mn ⁺⁺ , Sn ⁺⁺ , Pb ⁺⁺ , Co ^{++ and the} like. As the basic inorganic metal compound, known basic inorganic fillers containing these metal ions can be used. Specifically, magnesium oxide, magnesium hydroxide, magnesium carbonate, zinc oxide, sodium hydroxide, carbonate Sodium, calcium oxide, calcium hydroxide, lithium hydroxide, lithium carbonate and the like can be mentioned, but hydroxides or monoxides are particularly recommended, and more preferably high reactivity with the base resin. It is recommended to use calcium hydroxide, magnesium oxide, more preferably calcium hydroxide.

  As described above, a predetermined amount of the (c) component and the (d) component with respect to the base resin containing the predetermined amount of the component (a) and the component (b) and the resin component containing the arbitrary component (e) By blending each of them, the thermal stability, fluidity and moldability are excellent, and a dramatic improvement in resilience can be imparted to the molded product.

  The blending amount of the component (c) and the component (d) is such that the blending amount of the component (c) is 100 parts by mass of the resin component appropriately blending the components (a), (b), and (e). 5 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, more preferably 18 parts by mass or more, and an upper limit of 80 parts by mass or less, preferably 40 parts by mass or less, more preferably 25 parts by mass or less. More preferably, it is 22 parts by mass or less, and the blending amount of component (d) is 0.1 part by mass or more, preferably 0.5 part by mass or more, more preferably 1 part by mass or more, further preferably 2 parts by mass or more, and the upper limit. As 10 parts by mass or less, preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and further preferably 5 parts by mass or less. (C) When there are too few compounding quantities of a component, melt viscosity will become low and workability will fall, and when too large, durability will fall. When the blending amount of the component (d) is too small, improvement in thermal stability and resilience is not observed, and when it is too large, the heat resistance of the golf ball material is lowered by an excessive basic inorganic metal compound.

  The above-mentioned resin component, component (c) and component (d) are blended in predetermined amounts, respectively, but 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% of the acid groups in the material. % Or more, more preferably 80 mol% or more is recommended. By such high neutralization, it is possible to more reliably suppress the exchange reaction that becomes a problem when only the above-mentioned base resin and fatty acid (derivative) are used, and to prevent the generation of fatty acids, Stability is remarkably improved, moldability is good, and a molded product having very excellent resilience compared to conventional ionomer resins can be obtained.

  Here, the degree of neutralization is the degree of neutralization of acid groups contained in the mixture of the base resin and the fatty acid (derivative) of the component (c), and the metal ion neutralized product of the random copolymer in the base resin. When the ionomer resin is used, the neutralization degree of the ionomer resin itself is different. When comparing the mixture of the present invention having the same degree of neutralization with only the ionomer resin having the same degree of neutralization, the mixture of the present invention contains a large amount of metal ions, so that ion crosslinking that contributes to improvement in resilience is present. Density can be increased and excellent resilience can be imparted to the molded product.

  In addition, in order to achieve both high neutralization and excellent fluidity more reliably, the acid group of the above mixture should be neutralized with a transition metal ion and an alkali metal and / or alkaline earth metal ion. Can do. Neutralization with transition metal ions is weaker in ion agglomeration than alkali (earth) metal ions, but by using these different types of ions in combination, neutralization of acid groups in the mixture results in fluidization. The improvement of the property can be aimed at.

  The molar ratio of the transition metal ion to the alkali metal and / or alkaline earth metal ion is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, still more preferably 30:70 to It is recommended that it is 70:30, particularly preferably 40:60 to 60:40. If the molar ratio of transition metal ions is too small, the effect of improving fluidity may not be sufficiently imparted, and if the molar ratio of transition metal ions is too large, the resilience may be lowered.

  Examples of the metal ions include zinc ions as transition metal ions, and at least one selected from sodium ions, lithium ions, magnesium ions, and the like as alkali metal ions or alkaline earth metal ions. Although an ion can be mentioned, these are not specifically limited.

  In order to obtain a mixture in which the desired amount of acid groups has been neutralized with a transition metal ion and an alkali metal ion or alkaline earth metal ion, a known method can be employed, for example, a transition metal ion (zinc ion) The method of summing is a method using zinc soap in the fatty acid derivative, and a zinc ion neutralized product (for example, a zinc ion neutralized ionomer resin) when blending the component (a) and the component (b) as the base resin. Examples of the method used include a method using a zinc compound such as zinc oxide as the basic inorganic metal compound of component (d).

  The resin material preferably has a melt flow rate adjusted to ensure fluidity particularly suitable for injection molding and improve moldability. In this case, the test temperature is 190 ° C. and the test load is 21.10 according to JIS-K7210. The melt flow rate (MFR) when measured according to 18N (2.16 kgf) is preferably 0.5 dg / min or more, more preferably 1 dg / min or more, still more preferably 1.5 dg / min or more, and particularly preferably 2 dg. It is recommended that the upper limit be adjusted to 20 dg / min or less, more preferably 10 dg / min or less, still more preferably 5 dg / min or less, and particularly preferably 3 dg / min or less. If the melt flow rate is too large or too small, the workability may be significantly reduced.

Next, the intermediate layer will be described.
The material hardness of the intermediate layer is not particularly limited, but is preferably in the range of 50 to 70, preferably 55 to 66, and more preferably 60 to 63 in terms of durometer D hardness. If it is softer than the above range, the spin distance may be excessively applied during a full shot and the flight distance may not be extended. On the contrary, if it is harder than the above range, the durability to cracking at the time of repeated hitting may be deteriorated, or the hit feeling at the time of carrying out a putter or a short approach may become too hard. The thickness of the intermediate layer is 0.7mm or more 2.0mm or less, preferably 0.9mm or more 1.7mm or less, more preferably 1.1mm or more 1.4mm or less. If it deviates from the range, the low spin effect due to the driver (W # 1) hit may not be sufficient and the flight distance may not be extended. On the other hand, if it is smaller than the above range, the durability against cracking at the time of repeated impacts may be deteriorated, or the durability at low temperatures may be deteriorated.

  The intermediate layer is formed mainly using a resin material that is the same or different from the material of the envelope layer described above, and it is particularly preferable to use an ionomer resin. Specific examples include sodium-neutralized ionomer resins such as (trade names) Himiran 1605 and 1601, and Surlyn 8120, and zinc-neutralized ionomer resins such as Himiran 1557 and 1706. Or in combination of two or more.

  Particularly preferable as the material for the intermediate layer is an embodiment in which a zinc neutralized ionomer resin and a sodium neutralized ionomer resin are mixed and used as a main material in order to achieve the object of the present invention. The blending ratio of zinc neutralization type / sodium neutralization type (mass ratio) is 25/75 to 75/25, preferably 35/65 to 65/35, and more preferably 45/55 to 55/45.

  If it deviates from the above ratio, the rebound of the ball will be too low to obtain the desired jump, the durability at repeated hits at normal temperature will deteriorate, and the crack durability at low temperature (below zero) May be worse.

  The surface hardness of the intermediate layer, specifically, the surface hardness of the sphere in which the core and the envelope layer are covered with the intermediate layer is not particularly limited, but the durometer D hardness is preferably 60 or more and 80 or less, more preferably. Is 63 or more and 77 or less, more preferably 67 or more and 73 or less. If it is softer than the above range, the spin distance may be excessively applied during a full shot and the flight distance may not be extended. On the contrary, if it is harder than the above range, the durability to cracking at the time of repeated hitting may be deteriorated, or the hit feeling at the time of carrying out a putter or a short approach may become too hard.

  Further, in the present invention, the surface hardness of the intermediate layer is higher than the core surface hardness, the envelope layer surface hardness, and the cover surface hardness, that is, the hardest layer is formed among the surfaces of each layer. To do.

  About the said intermediate | middle layer material, in order to improve the adhesiveness with the polyurethane used with the cover mentioned later, it is suitable to grind | polish the intermediate | middle layer surface. Furthermore, it is preferable to apply a primer (adhesive) to the surface of the intermediate layer after the polishing treatment, or to add an adhesion reinforcing material in the material. Examples of the adhesion reinforcing material blended in the material include organic compounds such as 1,3-butanediol and trimethylolpropane, and oligomers such as polyethylene glycol and polyhydroxy polyolefin oligomer. In particular, trimethylolpropane and polyhydroxy polyolefin oligomer are preferably used. As these commercial products, for example, trimethylolpropane manufactured by Mitsubishi Gas Chemical Co., Ltd., polyhydroxypolyolefin oligomer manufactured by Mitsubishi Chemical Co., Ltd. (the main chain has 150 to 200 carbon atoms, and has a hydroxyl group at the end. Trade name Polytail H), etc. Can be mentioned.

  Next, the cover will be described. The cover referred to in the present invention means the outermost layer in the ball structure, and the intermediate layer and the envelope layer referred to in the present invention are excluded.

The cover has a durometer D hardness of 46 or more and 54 or less. If it is smaller than the above range, the spin distance may not be extended due to excessive spin during full shot. On the other hand, if the range is larger than the above range, there is a possibility that professionals and advanced players do not have sufficient controllability without taking spin in the approach.

  The thickness of the cover is not particularly limited, but is preferably from 0.3 mm to 1.5 mm, preferably from 0.5 mm to 1.2 mm, more preferably from 0.7 mm to 1.0 mm. It is. If it is thicker than the above range, the rebound of the ball may be insufficient when it is hit by the driver (W # 1), or the spin amount may increase, resulting in an increase in flight distance. On the other hand, if it is thinner than the above range, the scratch resistance may be deteriorated, or the controllability may be insufficient even for professionals and advanced players.

  In the present invention, the cover material is mainly made of polyurethane, thereby obtaining the effects of the present invention satisfying both controllability and scratch resistance.

Specifically, in this invention, the cover molding material (C) which has the following (A) and (B) component as a main component is employ | adopted.
(A) Thermoplastic polyurethane material (B) A thermoplastic resin (b-2) that does not substantially react with isocyanate with an isocyanate compound (b-1) having two or more isocyanate groups as functional groups in one molecule. ) Isocyanate mixture dispersed in

Hereinafter, components (A), (B) and (C) will be described.
(A) Thermoplastic polyurethane material The thermoplastic polyurethane material has a soft segment composed of a polymer polyol (polymeric glycol), a chain extender constituting a hard segment, and a diisocyanate. Here, as the raw material polymer polyol, any of those conventionally used in the technology relating to thermoplastic polyurethane materials can be used, and is not particularly limited. The polyether type is preferable to the polyester type in that a thermoplastic polyurethane material having a high elastic modulus and excellent low-temperature characteristics can be synthesized. Examples of the polyether polyol include polytetramethylene glycol and polypropylene glycol. Polytetramethylene glycol is particularly preferable from the viewpoint of the resilience modulus and low temperature characteristics. The average molecular weight of the polymer polyol is preferably 1000 to 5000, and particularly preferably 2000 to 4000 in order to synthesize a thermoplastic polyurethane material having high resilience.

  As the chain extender, those used in the conventional technology relating to thermoplastic polyurethane materials can be suitably used. For example, 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1 , 6-hexanediol, 2,2-dimethyl-1,3-propanediol and the like, but are not limited thereto. These chain extenders preferably have an average molecular weight of 20 to 15000.

  As the diisocyanate, those used in the conventional technology relating to thermoplastic polyurethane materials can be suitably used. For example, aromatics such as 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, and 2,6-toluene diisocyanate can be used. Aliphatic diisocyanates, aliphatic diisocyanates such as hexamethylene diisocyanate, and the like, but are not limited thereto. However, some isocyanate species make it difficult to control the crosslinking reaction during injection molding. In the present invention, 4,4'-diphenylmethane diisocyanate, which is an aromatic diisocyanate, is most preferred from the viewpoint of stability of reactivity with the isocyanate mixture (B) described later.

  As the thermoplastic polyurethane material, commercially available products can be suitably used. For example, Pandex T-8290, T-8295, T-8260 manufactured by DIC Bayer Polymer Co., Ltd., and Dainichi Seika Kogyo Co., Ltd. Resamine 2593, 2597 and the like can be mentioned.

(B) Isocyanate mixture Isocyanate mixture (B) is a thermoplastic resin (b-2) that does not substantially react with isocyanate with an isocyanate compound (b-1) having two or more isocyanate groups as functional groups in one molecule. ). Here, as said isocyanate compound (b-1), what is used in the technique regarding the conventional thermoplastic polyurethane material can be used suitably, for example, 4,4'- diphenylmethane diisocyanate, 2, 4-toluene diisocyanate. , Aromatic diisocyanates such as 2,6-toluene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate, but are not limited thereto. However, 4,4′-diphenylmethane diisocyanate is optimal in terms of reactivity and work safety.

  The thermoplastic resin (b-2) is preferably a resin having low water absorption and excellent compatibility with the thermoplastic polyurethane material. Examples of such resins include polystyrene resins, polyvinyl chloride resins, ABS resins, polycarbonate resins, and polyester elastomers (polyether / ester block copolymers, polyester / ester block copolymers, etc.). From the viewpoint of strength, a polyester elastomer, particularly a polyether / ester block copolymer is particularly preferable.

  The blending ratio of the thermoplastic resin (b-2): isocyanate compound (b-1) in the isocyanate mixture (B) is 100: 5 to 100: 100, particularly 100: 10 to 100: 40, in mass ratio. preferable. When the blending amount of the isocyanate compound (b-1) with respect to the thermoplastic resin (b-2) is too small, in order to obtain a sufficient addition amount for the crosslinking reaction with the thermoplastic polyurethane material (A), a larger amount of the isocyanate mixture (B) must be added, and the physical properties of the cover molding material (C) become insufficient due to the great influence of the thermoplastic resin (b-2). When the amount of the isocyanate compound (b-1) is too large relative to the thermoplastic resin (b-2), the isocyanate compound (b-1) causes a slip phenomenon during kneading, and it is difficult to synthesize the isocyanate mixture (B). It becomes.

  The isocyanate mixture (B) is prepared by, for example, blending the isocyanate compound (b-1) with the thermoplastic resin (b-2), and kneading them sufficiently with a mixing roll or Banbury mixer at a temperature of 130 to 250 ° C. Or by cooling after cooling. A commercially available product can be suitably used as the isocyanate mixture (B), and examples thereof include Crossnate EM30 manufactured by Dainichi Seika Kogyo Co., Ltd.

(C) Cover molding material The cover molding material (C) is mainly composed of the thermoplastic polyurethane material (A) and the isocyanate mixture (B) described above. The blending ratio of the thermoplastic polyurethane material (A): isocyanate mixture (B) in the cover molding material (C) is 100: 1 to 100: 100, particularly 100: 5 to 100: 50, particularly 100: 10, in mass ratio. It is preferable that it is 100: 30. If the blending amount of the isocyanate mixture (B) with respect to the thermoplastic polyurethane material (A) is too small, the crosslinking effect is not sufficiently exhibited, and if it is too large, the unreacted isocyanate causes a coloring phenomenon in the molded product.

  In addition to the components described above, other components can be blended in the cover molding material (C). Examples of such other components include thermoplastic polymer materials other than thermoplastic polyurethane materials. For example, polyester elastomers, polyamide elastomers, ionomer resins, styrene block elastomers, polyethylene, nylon resins and the like can be blended. it can. In this case, the blending amount of the thermoplastic polymer material other than the thermoplastic polyurethane material is 0 to 100 parts by weight, preferably 1 to 75 parts by weight, more preferably 100 parts by weight of the thermoplastic polyurethane material which is an essential component. It is 10-50 mass parts, and is suitably selected according to adjustment of the hardness of a cover material, improvement of resilience, improvement of fluidity, improvement of adhesiveness, etc. Furthermore, the cover molding material (C) can be blended with various additives as necessary. For example, pigments, dispersants, antioxidants, light stabilizers, ultraviolet absorbers, and release agents are blended as appropriate. can do.

  In the molding of the cover using the cover molding material (C), for example, the isocyanate mixture (B) is added to the thermoplastic polyurethane material (A) and dry-mixed, and this mixture is used around the core by an injection molding machine. The cover can be molded. The molding temperature varies depending on the type of the thermoplastic polyurethane material (A), but is usually in the range of 150 to 250 ° C.

  As a reaction form and a crosslinked form of the golf ball cover obtained as described above, an isocyanate group reacts with a residual OH group of a thermoplastic polyurethane material to form a urethane bond, or a urethane group of a thermoplastic polyurethane material. It is considered that an addition reaction of an isocyanate group occurs to form an allophanate or burette crosslinked form. In this case, the cross-linking reaction does not proceed sufficiently immediately after the injection molding of the cover molding material (C), but the cross-linking reaction proceeds by performing annealing after molding, and retains useful characteristics as a golf ball cover. . Annealing means that the cover is aged by heating at a constant temperature for a certain period of time, or aged for a certain period at room temperature.

  In addition to the resin component, various additives can be blended in the resin material of the envelope layer, the intermediate layer, and the cover as described above, if necessary. Examples of such additives include pigments, dispersants, antioxidants, UV absorbers, UV stabilizers, mold release agents, plasticizers, inorganic fillers (such as zinc oxide, barium sulfate, and titanium dioxide). be able to.

In the present invention, the surface hardness relationship between the intermediate layer and the cover is optimized. That is, the surface hardness of the intermediate layer and the cover (durometer D hardness) needs to satisfy the condition of intermediate layer surface hardness> cover surface hardness. In this case, when the envelope layer is included, it is preferable that the relationship between these three layers satisfies the condition of envelope layer surface hardness <intermediate layer surface hardness> cover surface hardness.

Relationship between the thickness of the envelope layer, the intermediate layer, and the cover In the present invention, the relationship between the thickness of the envelope layer, the intermediate layer, and the cover is as follows: the condition of cover thickness <interlayer thickness <envelop layer thickness It is necessary to satisfy . By optimizing the thickness of each layer, it is possible to obtain a golf ball having both flying, controllability, durability, and feel. If the cover is thicker than the intermediate layer, the ball repulsion may be low, or the spin distance may not be extended due to excessive spin during a full shot. Also, if the envelope layer is thinner than the intermediate layer, the low spin effect may be insufficient and a desired target flight distance may not be obtained.

  A method for producing a multi-piece solid golf ball that is formed by laminating the core, envelope layer, intermediate layer, and cover described above can be performed by a conventional method such as a known injection molding method. For example, a vulcanized molded product mainly composed of a rubber material is disposed in a predetermined injection mold as a core, and in order, an envelope layer material and an intermediate layer material are injected to obtain an intermediate spherical body, A multi-piece golf ball can be obtained by arranging the spherical body in another injection mold and injection molding the cover material. Further, the cover can be laminated by a method of covering the cover with an intermediate spherical body. For example, the intermediate spherical body can be wrapped in two half cups that have been previously formed into a half-shell spherical shape and heat-pressed. .

  The surface hardness of the golf ball of the present invention is determined by the hardness of the material used in each layer, the hardness of each layer, and the hardness of the base. The durometer D hardness is usually 55 to 70, preferably 57. It is 68 or less and more preferably 59 or more and 66 or less. If it is smaller than the above range, the spin may be applied too much and the flight distance may not be extended. On the other hand, if the range is larger than the above range, there is a possibility that professionals and advanced players do not have sufficient controllability without taking spin in the approach.

  The surface hardness of the golf ball of the present invention is preferably made softer in the range of 1 to 10, preferably 2 to 8, and more preferably 3 to 6 in terms of durometer D hardness than the intermediate layer surface hardness. If it is less than the above range, the spin in the approach will not be applied, and even professionals and advanced players may lack control. If it is larger than the above range, the resilience may be insufficient, or the spin may be excessively applied during a full shot, and a desired flight distance may not be obtained.

  In addition, a large number of dimples can be formed on the cover surface. The dimples arranged on the surface of the cover are not particularly limited, but may preferably include 280 or more and 360 or less, more preferably 300 or more and 350 or less, and further preferably 320 or more and 340 or less. If the number of dimples exceeds the above range, the trajectory of the ball may be lowered and the flight distance may be reduced. Conversely, when the number of dimples decreases, the trajectory of the ball increases and the flight distance may not increase.

  About the shape of a dimple, it can use suitably combining 1 type or 2 types or more, such as circular, various polygons, a dew drop shape, and other ellipses. For example, when circular dimples are used, the diameter can be about 2.5 mm to 6.5 mm and the depth can be 0.08 mm to 0.30 mm.

The dimple occupancy ratio that the dimples occupy on the spherical surface of the golf ball, specifically, the sum of the dimple areas defined by the surface edges of the plane surrounded by the edges of the dimples occupies the ball sphere area assuming that no dimples exist About a ratio (SR value), it is desirable that it is 60% or more and 90% or less from the point which can fully exhibit aerodynamic characteristics. Further, a value V _{0 obtained} by dividing the space volume of the dimple below the plane surrounded by the edge of each dimple by the volume of the cylinder having the plane as the bottom and the maximum depth of the dimple from the bottom as a height is: From the viewpoint of optimizing the trajectory of the ball, it is preferable to set it to 0.35 or more and 0.80 or less. Furthermore, the VR value occupying the ball ball volume assuming that the dimple volume formed below the plane surrounded by the edge of the dimple does not exist is 0.6% to 1.0%. Is preferred. If the value deviates from the above ranges, the trajectory may not provide a good flight distance, and a sufficiently satisfactory flight distance may not be obtained.

  The golf ball of the present invention can be used for competition purposes and comply with the golf regulations. The outer diameter of the ball is 42.80 mm or less, and the weight is usually 45.72 mm. It can be formed from 0 to 45.93 g.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Examples 1 to 3, Comparative Examples 1 to 6]
Formation of Core After adjusting the rubber composition by the formulation shown in Table 1, a core was prepared by vulcanization molding under the vulcanization conditions in Table 1. For Comparative Example 4, after blending and vulcanizing the rubber composition according to the formulation shown in Table 2, the outer core (enveloping layer) is wrapped around the center core in an unvulcanized state, and the sphere is vulcanized and molded. Were laminated.

In addition, the brand name of the main material described in the table | surface is as follows.
Polybutadiene product name "BR730" (Nd-based catalyst), manufactured by JSR
Mixture of peroxide 1,1-di (t-butylperoxy) cyclohexane and silica, trade name “Perhexa C-40”
Anti - aging agent 2,2′-methylene-bis (4-methyl-6-tert-butylphenol), trade name “NOCRACK NS-6” manufactured by Ouchi Shinsei Chemical Co., Ltd.

Formation of envelope layer, intermediate layer and cover Next, the envelope layer, intermediate layer and cover blended with various resin components shown in Table 3 were molded by injection molding, and the envelope layer, intermediate layer around the core The cover was sequentially coated and formed. For the envelope layer of Comparative Example 4, a rubber material was used as described above. And the multi-piece solid golf ball which formed the dimple on the cover surface using the common dimple shown in Table 4 was created.

In addition, the brand name of the main material described in the table | surface is as follows.
High Milan: Made by Mitsui DuPont Polychemical Co., Ltd. Ionomer Resin Surlyn: Made by DuPont Ionomer Resin AN4311: Made by Mitsui DuPont Polychemical Co., Ltd. Nitric acid: NAF222-S beads designated by Nippon Oil & Fats Co., Ltd. Specified calcium hydroxide: CLS-B designated polytail H manufactured by Shiraishi Kogyo Co., Ltd. Low molecular weight polyolefin polyol pandex manufactured by Mitsubishi Chemical Corporation MDI-PTMG type manufactured by DIC Bayer Polymer Thermoplastic Polyure
Tan Isocyanate Compound: Trade name “Crosnate EM30” manufactured by Dainichi Seika Kogyo Co., Ltd.
4,4'-diphenylmethane diisocyanate in anate masterbatch
Containing 30%. Amine back titration isocyan according to JIS-K1556
Nate measurement concentration 5-10%, masterbatch base resin is polyester ether
Lastomer was used. In addition, the isocyanate compound is panned during injection molding.
Used mixed with dex.

Dimples Definition <br/> diameter: diameter depth flat plane circumscribed by an edge of the dimple: maximum depth of the dimple from the plane surrounded by the edge of the dimple V _0: under flat plane circumscribed by an edge of the dimple A value obtained by dividing the spatial volume of the dimple by a cylindrical volume having the plane as the bottom surface and the maximum depth of the dimple from the bottom surface as a height SR: a dimple defined by the surface edge of the plane surrounded by the edge of the dimple The ratio of the total area to the ball sphere area assuming that no dimples exist VR: The total dimple volume formed below the plane surrounded by the edges of the dimples is the ball assuming that no dimples exist Proportion of ball volume

  For each of the obtained golf balls of Examples 1 to 3 and Comparative Examples 1 to 6, the surface hardness and other physical properties of each layer and the ball, flying performance, approach spin (controllability), repeated impact durability, and scratch resistance Was evaluated according to the following criteria. The results are shown in Table 5. In addition, all measured in 23 degreeC environment.

(1) Deflection amount of the core The core deflection amount (mm) when the core is placed on a hard plate and loaded from an initial load of 98 N (10 kgf) to a final load of 1,275 N (130 kgf).

(2) Core surface hardness The surface of the core is a spherical surface. Set the surface of the hardness meter so that the surface of the core is almost perpendicular to the surface of the core, and use the durometer D hardness (ASTM-2240 standard durometer type D) to The average value of the values measured randomly at two points.

(3) Material hardness of envelope layer The resin material of the envelope layer was formed into a sheet shape having a thickness of 2 mm, and measured by a durometer “type D” of ASTM-2240 standard.

(4) The surface hardness of the sphere coated with the envelope layer was set so that the needle of the hardness meter was almost perpendicular to the envelope layer surface, which was a spherical surface hardness , and measured according to ASTM D2240.

(5) Intermediate layer material hardness This is the same measurement method as in (3) above.

(6) The surface hardness of the sphere coated with the intermediate layer The surface of the intermediate layer, which is a spherical surface, was set so that the needle of the hardness meter was almost vertical, and the measurement was performed according to ASTM D2240.

(7) Material hardness of the cover This is the same measurement method as in (3) above.

(8) Surface hardness of the ball The hardness tester was set so that the surface of the ball surface was free of dimples and was measured according to ASTM D2240.

(9) About the carry and total when a flying club (Bridgestone Sports Co., Ltd., "BEAM Z model 430" (loft angle 10.5 °) is mounted on a striking robot and hit with a head speed (HS) of 45 m / s. The following criteria were used for the evaluation, and the spin amount was a value obtained by measuring the ball immediately after hitting with an initial condition measuring device.
○: Total distance over 240m
×: Total flight distance less than 240m

(10) Approach spin amount Using a wedge wedge (SW) (manufactured by Bridgestone Sports Co., Ltd., J's Classical Edition), the spin amount when hit with HS 22 m / s was measured. The following criteria were used for the evaluation. The spin amount was measured by the same method as the above flight distance measurement.
○: Spin amount 6500 rpm or more
X: Spin amount less than 6500 rpm

(11) Repeated hitting durability A golf hitting robot with a W # 1 club was hit repeatedly at a head speed of 40 m / s. Each index when the number of times when the initial speed of the ball of Example 3 was 97% or less compared to the initial initial average of 10 times was 100 was evaluated according to the following criteria. The average value of each ball N = 3 was used as the evaluation target value.
○: Index 90 or higher
X: Index less than 90

(12) A scratch-resistant non-plated pitching sand wedge was set on a striking robot, hit once at a head speed of 40 m / s, and the surface of the ball was visually observed and evaluated according to the following criteria.
Y: Can still be used
×: Cannot be used anymore

  From the results of Table 5, in Comparative Example 1, the cover (outer layer) was too hard, so that the approach spin was not sufficiently applied and the scratch resistance was poor. In Comparative Example 2, the envelope layer material was a normal ionomer, the ball rebound was slightly low, and the repeated hitting durability was poor. In Comparative Example 3, the cover (outer layer) material was an ionomer, and the scratch resistance was poor. In Comparative Example 4, the envelope layer was formed of a rubber material, and as a result, the crack durability during repeated hitting was poor. In Comparative Example 5, the envelope layer material was a polyester material, and the spin amount increased and the flight distance did not increase. Comparative Example 6 is a three-piece golf ball in which a core without an envelope layer is coated with two layers. This ball still has a large amount of spin and does not extend its flight distance.

It is a schematic sectional drawing of the multi-piece solid golf ball (four-layer structure) of this invention. It is a top view of the golf ball showing the arrangement mode of the dimples used in this example.

Explanation of symbols

G Golf ball 1 Core 2 Enveloping layer 3 Intermediate layer 4 Cover D Dimple

Claims (2)

A core composed of a single layer, an envelope layer having a thickness of 1.0 to 4.0 mm for covering the core, an intermediate layer having a thickness of 0.7 to 2.0 mm for covering the core, and covering the surface, In a multi-piece solid golf ball provided with a cover on which a large number of dimples are formed, the core is formed of polybutadiene and the core has a diameter of 31 mm or more, and an initial load of 98 N is applied to the core. The amount of deflection (mm) from (10 kgf) to when a final load of 1,275 N (130 kgf) is applied is in the range of 2.0 mm to 5.0 mm, and the envelope layer is (a) an olefin-unsaturated carboxylic acid. Binary random copolymer and / or olefin-unsaturated carboxylic acid binary random copolymer metal ion neutralized product, and (b) olefin-unsaturated carboxylic acid-unsaturated carboxylic acid The mass ratio of the ester ternary random copolymer and / or the metal ion neutralized product of the olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer is 100: 0 to 0: 100. Blended base resin,
(E) Non-ionomer thermoplastic elastomer and 100 parts by mass of a resin component formulated so as to have a mass ratio of 100: 0 to 50:50,
(C) 5-80 parts by mass of a fatty acid having a molecular weight of 280-1500 and / or a derivative thereof;
(D) The base resin and a basic inorganic metal compound capable of neutralizing an unneutralized acid group in the component (c) are formed as a main material, a mixture containing 0.1 to 10 parts by mass as an essential component, The intermediate layer is formed mainly of a resin material, and the cover is
(A) a thermoplastic polyurethane material;
(B) an isocyanate mixture in which an isocyanate compound (b-1) having two or more isocyanate groups as a functional group in one molecule is dispersed in a thermoplastic resin (b-2) that does not substantially react with isocyanate; And the cover has a durometer D hardness of 46 or more and 54 or less, and the intermediate layer and the cover have a surface hardness (durometer D hardness) of intermediate layer surface hardness> A multi-piece solid golf ball that satisfies the condition of the cover surface hardness and the thickness of the envelope layer, intermediate layer, and cover satisfies the condition of cover thickness <interlayer thickness <envelop layer thickness .   The multi-piece solid golf ball according to claim 1, wherein a hardness relationship between the envelope layer and the intermediate layer satisfies a condition of envelope layer surface hardness <intermediate layer surface hardness.

Images